Those who have family within the US typically get to stay there. According to the Migration Policy Institute, some get foster care (link ).
Update: July 15
WJLA-7 reports that some migrant children are being housed at undisclosed locations in Prince William County, 30 miles or so south of Washington DC, and are depending on charitable or religious organizations to provide care. The article suggests that some immigration judges will allow some to stay because of threats of violence, but does this depend on secondary volunteerism? Details are sketchy,.
Second picture: Smithsonian (Kenya).